Energy
The ability to do work is called __.
energy
Which of the following has kinetic energy?
a. a rock poised for a fall
b. an archer’s bow that is drawn back
c. a rolling bowling ball
d. a car waiting at a red light
c. a rolling bowling ball
Which of these is an example of work being done on an object?
b. trying to push a car that doesn’t move out of deep snow
c. pushing a child on a swing
d. holding a door shut on a windy day so it doesn’t blow open
c. pushing a child on a swing
Which body parts act as the fulcrums of levers?
a. muscles b. bones c. joints d. tendons
joints
Work equals force times __.
distance
Energy is measured in units called __.
joules
Unlike kinetic energy, potential energy is __.
stored
If you exert a force of 20 Newtons to push a desk 10 meters, how much work do you do on the desk?
200 joules
Which body parts are shaped like wedges?
a. muscles b. tendons c. incisors d. bones in your legs
c. incisors
When you raise or lower a flag on a flagpole, you are using a (an) __.
pulley
The energy associated with motion is called __.
kinetic energy
Potential energy that depends on height is called __.
gravitational potential energy
What do machines do?
change the amount of force you exert or the distance over which you exert the force
What simple machine is considered an inclined plane wrapped around a cylinder?
screw
Most of the machines in your body consist of bones and muscles and are called __.
levers
When you rub your hands together on a cold day, you use friction to convert __.
mechanical into thermal energy
How would you calculate an object’s mechanical energy?
add its kinetic and potential energies
True or False: Scissors are an example of a lever.
true
The fixed point that a lever pivots around is called the __.
fulcrum
Complete the statement: The __ energy of a book on a shelf is equal to the work done to lift the book to the shelf.
gravitational potential
The type of energy stored by fossil fuels such as coal is __.
chemical energy
For work to be done on an object, __.
a. some force need only be exerted on the object
b. the object must move some distance as a result of a force
c. the object must move, whether or not a force is exerted on it
d. the object must not move
b. the object must move some distance as a result of a force
True or False: A bicycle an example of a compound machine?
True
In order to do work on an object, the force you exert must be __.
in the same direction as the object’s motion
Power is equal to __ divided by time.
work